So I am using coroutines 1 6 and in my data source I have th

Question

So I am using coroutines 1 6 and in my data source I have this method ```override fun sumSelectedFees Single lt Float gt = rxSingle workDispatcher dao findDeliveryModeShippingOptions true fold 0f total shippingOption gt total + shippingOption feeValue ``` and I trying to call this in my test ``` Test fun `should sum all inserted fees for delivery` = runTest val dataSource = dataSource = DeliveryModesDataSourceImpl dao UnconfinedTestDispatcher dataSource sumSelectedFees test assertValue 0f ``` but my test is failing since the test is not waiting the rx call ` test ` to complete I Used `UnconfinedTestDispatcher` here but I am not sure what I dispatcher I should be using in this case

Sam · Answer

~I m guessing the problem is the `workDispatcher` you re passing to `rxSingle` The test doesn t know anything about that dispatcher and so can t wait for it to finish ~

Sam · Answer

~You ll need to find a way to pass the dispatcher from the test into the `sumSelectedFees` method ~

Sam · Answer

~One option would be ~

Sam · Answer

```override fun sumSelectedFees context CoroutineContext = workDispatcher Single lt Float gt = rxSingle context ```

juliocbcotta · Answer

I do pass the Dispatcher in the constructor ```val dataSource = DeliveryModesDataSourceImpl dao UnconfinedTestDispatcher ```

Sam · Answer

Yeah I just realised that face palm sorry

Sam · Answer

In that case I think the problem is just that the `UnconfinedTestDispatcher` you use isn t the same one being used by `runTest`

Sam · Answer

Try to get the existing dispatcher from the `TestScope` and pass it to the `DeliveryModesDataSourceImpl` instead of creating a new `UnconfinedTestDispatcher`

Sam · Answer

Or create your dispatcher outside the test and pass it into both `runTest` and the `DeliveryModesDataSourceImpl`

juliocbcotta · Answer

I changed my code to use ```private val dispatcher = UnconfinedTestDispatcher ``` ```dataSource = DeliveryModesDataSourceImpl dao dispatcher ``` ```runTest dispatcher ``` Still not working

Sam · Answer

Maybe after the ` test ` and before the ` assertValue ` you need to call `runCurrent `

Sam · Answer

Even the `UnconfinedTestDispatcher` won t always run all of its coroutines without a call to `runCurrent` if they re nested launched in more complicated ways

juliocbcotta · Answer

I tried it too didn t help

Sam · Answer

I m out of ideas then shrug sorry Although I ve tested a lot of coroutines I haven t worked with `rxSingle` There must be a trick we re missing

juliocbcotta · Answer

Me too this is so frustrating

Dmitry Khalanskiy [JB] · Answer

Try `UnconfinedTestDispatcher testScheduler ` instead of just `UnconfinedTestDispatcher` Otherwise there s no link between `runTest` and the dispatcher unless there s `Dispatchers setMain` somewhere

juliocbcotta · Answer

I am not calling `Dispatchers setMain` but I am using `runTest dispatcher ` where `val dispatcher = UnconfinedTestDispatcher `

Dmitry Khalanskiy [JB] · Answer

Then `UnconfinedTestDispatcher ` just creates a new dispatcher not related to `runTest`

juliocbcotta · Answer

Sorry I think I didn t understand what you mean I am just trying to make the test work by connecting the dots I need the `rxSingle` to publish in a sync way so ` test ` will be sync and so my test I passed around the Dispatcher to every place I could find but my tests are still failing

Dmitry Khalanskiy [JB] · Answer

``` Test fun `should sum all inserted fees for delivery` = runTest val dataSource = dataSource = DeliveryModesDataSourceImpl dao UnconfinedTestDispatcher testScheduler lt modified here dataSource sumSelectedFees test assertValue 0f ```

juliocbcotta · Answer

My results are the same ```expected 0 0 class Float but was latch = 1 values = 0 errors = 0 completions = 0 java lang AssertionError expected 0 0 class Float but was latch = 1 values = 0 errors = 0 completions = 0 ```

juliocbcotta · Answer

I think I was able to reproduce the problem with a simpler more generic version of the code ```private val dispatcher = UnconfinedTestDispatcher suspend fun bar = withContext dispatcher withContext <http Dispatchers IO|Dispatchers IO> 1 Test fun foo = runTest dispatcher rxSingle dispatcher bar test assertValue 1 assertComplete ```

Dmitry Khalanskiy [JB] · Answer

This isn t really related to coroutines this is due to `test ` in RxJava not awaiting the completion For example here is the same issue without any coroutines ``` Test fun foo2 val single = Single create lt Int gt emitter gt thread Thread sleep 10 emitter onSuccess 1 single test assertValue 1 assertComplete ``` It may work if there s only one thread but `<http Dispatchers IO|Dispatchers IO>` uses other threads This can be fixed with ``` Test fun foo = runTest dispatcher rxSingle dispatcher bar test await lt waits for completion before checking the results assertValue 1 assertComplete ```

juliocbcotta · Answer

Ohh thanks I didn t know that